Optical microscopy and spectroscopy includes a large number of techniques and applications. Example techniques include differential interference contrast, phase contrast and dark field microscopy, absorption microscopy, coherent interferometric microscopy, Raman spectroscopy and microscopy, and fluorescence based techniques, such as fluorescence resonance energy transfer (FRET) spectroscopy, fluorescence life-time imaging, fluorescence polarization and anisotropy microscopy, multi-colour, alternating-laser excitation microscopy, single-particle localization and structured illumination based super-resolution microscopy.
For many applications, the microscope system must be extremely stable, protected from vibration and other external influences, precisely aligned and controlled, able to detect extremely weak signals, and safe to operate. Commercially available systems and bespoke microscopy systems for specific applications can be expensive and have large dimensions and weight, and are consequently not portable, while requiring substantial infrastructure, maintenance costs, operator training and custom software, and a consequent substantial total cost of ownership.